U.S. patent application number 14/921469 was filed with the patent office on 2016-04-28 for engine control apparatus.
The applicant listed for this patent is DENSO CORPORATION. Invention is credited to Takuya GOTOU, Kazunari IZUMI, Kazutoshi KUWAYAMA.
Application Number | 20160114652 14/921469 |
Document ID | / |
Family ID | 55791307 |
Filed Date | 2016-04-28 |
United States Patent
Application |
20160114652 |
Kind Code |
A1 |
IZUMI; Kazunari ; et
al. |
April 28, 2016 |
ENGINE CONTROL APPARATUS
Abstract
A control apparatus is applied to a system including an engine
and a compressor for air-conditioning, and adjusts an operating
point of the engine when the engine is operated. The control
apparatus determines whether or not to allow increase in engine
output to drive a compressor based on an air-conditioning request,
based on the operating point of the engine before driving of the
compressor in relation to a predetermined high-efficiency region
including a maximum efficiency point in an efficiency
characteristics of the engine, when the compressor is driven in
response to the air-conditioning request. The control apparatus
controls the engine output such that the operating point of the
engine is in the high-efficiency region, if the increase in engine
output is determined to be allowed.
Inventors: |
IZUMI; Kazunari;
(Kariya-shi, JP) ; KUWAYAMA; Kazutoshi;
(Kariya-shi, JP) ; GOTOU; Takuya; (Kariya-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION |
Kariya-city |
|
JP |
|
|
Family ID: |
55791307 |
Appl. No.: |
14/921469 |
Filed: |
October 23, 2015 |
Current U.S.
Class: |
701/36 ;
180/65.265; 903/930 |
Current CPC
Class: |
B60W 10/30 20130101;
B60W 2510/0657 20130101; B60W 20/11 20160101; B60H 1/3208 20130101;
B60W 2710/0677 20130101; B60W 2710/305 20130101; B60K 6/445
20130101; B60W 10/06 20130101; Y02T 10/62 20130101; B60H 2001/3273
20130101; B60W 20/13 20160101; B60W 20/10 20130101; Y10S 903/93
20130101; B60W 2510/30 20130101; B60W 2710/0666 20130101; Y02T
10/40 20130101 |
International
Class: |
B60H 1/32 20060101
B60H001/32; B60R 16/033 20060101 B60R016/033; B60W 20/10 20060101
B60W020/10; B60H 1/00 20060101 B60H001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2014 |
JP |
2014-219636 |
Jan 29, 2015 |
JP |
2015-015116 |
Claims
1. A control apparatus that is applied to a system including an
engine and a compressor for air-conditioning, and adjusts an
operating point of the engine when the engine is operated, the
control apparatus comprising: an allowed/not-allowed determiner
means that determines whether or not to allow increase in engine
output to drive a compressor based on an air-conditioning request,
based on the operating point of the engine before driving of the
compressor in relation to a predetermined high-efficiency region
including a maximum efficiency point in efficiency characteristics
of the engine, when the compressor is driven in response to the
air-conditioning request; and a controller means that controls the
engine output such that the operating point of the engine is in the
high-efficiency region, if the increase in engine output is
determined to be allowed.
2. The control apparatus according to claim 1, wherein: the
allowed/not-allowed determiner means is configured to determine to
allow the increase in engine output if the operating point of the
engine before driving of the compressor becomes closer to the
high-efficiency region by surplus output of the engine when the
compressor is driven in response to the air conditioning request;
and the controller means is configured to increase the engine
output such that the operating point of the engine becomes in the
high-efficiency region, if the increase in engine output is
determined to be allowed for the surplus output.
3. The control apparatus according to claim 2, further comprising:
an increasable output calculator means that calculates an
increasable output by which the engine output can be increased
without exceeding the high-efficiency region in in the efficiency
characteristics of the engine, based on the operating point of the
engine before driving of the compressor; and a determiner means
that determines whether or not a requested driving output for the
compressor upon driving of the compressor is greater than the
increasable output calculated by the increasable output calculator
means, wherein the controller means is configured to add, to a
current engine output, an amount of increase corresponding to the
increasable output, if the increase in engine output is determined
to be allowed for the surplus output and if the requested driving
output for the compressor is greater than the increasable
output.
4. The control apparatus according to claim 3, wherein the
controller means is configured to add, to a current engine output,
an amount of increase corresponding to the requested driving output
for the compressor, if the increase in engine output is determined
to be allowed for the surplus output and if the requested driving
output for the compressor is less than the increasable output.
5. The control apparatus according to claim 3, wherein the
requested driving output for the compressor is a power for enabling
the compressor to be driven in a predetermined high efficiency
state.
6. The control apparatus according to claim 2, wherein: the control
apparatus is applied to a system including a battery capable of
being charged by the engine; and the control apparatus further
comprises: an increasable output calculator means that calculates
an increasable output capable of increasing the engine output
without exceeding the high-efficiency region in in the efficiency
characteristics of the engine, based on the operating point of the
engine before driving of the compressor; and a determiner means
that determines whether or not a total requested driving output is
greater than the increasable output calculated by the increasable
output calculator means, the total requested driving output being a
sum of a requested driving output for the compressor upon driving
of the compressor and a requested charging power for the battery
upon charging of the battery, wherein the controller means is
configured to add, to a current engine output, an amount of
increase corresponding to the increasable output, if the increase
in engine output is determined to be allowed for the surplus output
and if the total requested driving output is greater than the
increasable output.
7. The control apparatus according to claim 6, wherein: the
controller means is configured to add, to a current engine output,
an amount of increase corresponding to the total requested driving
output, if the increase in engine output is determined to be
allowed for the surplus output and if the total requested driving
output is less than the increasable output.
8. The control apparatus according to claim 6, further comprising:
an output controller means that performs control to supply surplus
power generated by the surplus output, wherein when the surplus
power can be supplied to both the compressor and the battery as
loads to which the surplus power is supplied, the output controller
means is configured to supply the surplus power to one of the loads
that has a higher priority level for power supply.
9. The control apparatus according to claim 8, wherein when an
amount of the surplus power supplied to one of the loads having a
high priority level for power supply exceeds an allowable amount,
the output controller means supplies a remaining surplus power to
the other of the loads.
10. The control apparatus according to claim 6, further comprising:
an output controller means that performs control to supply surplus
power generated by the surplus output, wherein the output
controller means is configured to supply the surplus power to the
compressor when the surplus power can be supplied to both the
compressor and the battery.
11. The control apparatus according to claim 8, wherein: the output
controller means is configured to determine a high priority level
for power supply of the surplus power generated by the surplus
output, based on a vehicle cabin temperature and a battery
characteristics of the battery.
12. The control apparatus according to claim 8, wherein: the
determiner means is configured to determine whether or not the
requested charging power for the battery is greater than the
increasable output when there is an abnormality in the
compressor.
13. The control apparatus according to claim 1, wherein: the
controller means is configured to alternatively perform an increase
in engine output and a pause of the increase during which the
air-conditioning request is generated.
14. The control apparatus according to claim 1, wherein: the
compressor is provided in an air-conditioning system including a
cold storage means that stores heat from a refrigerant circulated
by driving of the compressor; and the controller means is
configured to perform control of the engine output such that the
operating point of the engine is in the high-efficiency region
within a cold storage period during which cold storage is performed
by the cold storage means, and to stop the control of the engine
output within a cold release period following the cold storage
period.
15. The control apparatus according to claim 1, further comprising:
a compressor drive determiner means that determines whether or not
the operating point of the engine becomes closer to the
high-efficiency region by decreasing an amount of increase in
engine output for driving the compressor, under a condition that
control of the engine output is performed by the controller means
and the compressor is driven, wherein the controller means is
configured to decrease the engine output if determined that the
operating point of the engine becomes closer to the high-efficiency
region by decreasing the amount of increase in the engine
output.
16. The control apparatus according to claim 15, further
comprising: a decreasable output calculator means that calculates a
decreasable output capable of decreasing the engine output without
exceeding the high-efficiency region in in the efficiency
characteristics of the engine, based on the operating point of the
engine in a state where the compressor is driven; and a determiner
means that determines whether or not a requested driving output for
the compressor upon driving of the compressor is greater than the
decreasable output calculated by the increasable output calculator
means, wherein the controller means is configured to subtract, from
a current engine output, an amount of decrease corresponding to the
decreasable output, if the requested driving output for the
compressor is greater than the decreasable output in a state where
the compressor is driven.
17. The control apparatus according to claim 16, wherein: the
controller means is configured to subtract, from a current engine
output, an amount of decrease corresponding to the requested
driving output for the compressor, if the requested driving output
for the compressor is less than the decreasable output in a state
where the compressor is driven.
18. The control apparatus according to claim 15, further
comprising: a request determiner means that determines whether or
not a current air-conditioning request is met even when an amount
of increase in the engine output for driving the compressor is
decreased, under a condition that control of the engine output is
performed by the control means and the compressor is driven,
wherein the controller means is configured to decrease the engine
output if determined that a current air-conditioning request is met
even when an amount of increase in the engine output for driving
the compressor is decreased.
19. The control apparatus according to claim 1, wherein: the
control apparatus is applied to a system including a power
generator means that generates heat by driving the engine; the
allowed/not-allowed determiner means is configured to determine to
allow the increase in engine output if the operating point of the
engine before driving of the compressor becomes closer to the
high-efficiency region by surplus output of the engine for surplus
power generation of the power generator means when the compressor
is driven in response to the air conditioning request.
20. A system comprising: an engine; a compressor for
air-conditioning; and a control apparatus that adjusts an operating
point of the engine when the engine is operated, the control
apparatus comprising: an allowed/not-allowed determiner means that
determines whether or not to allow increase in engine output to
drive a compressor based on an air-conditioning request, based on
the operating point of the engine before driving of the compressor
in relation to a predetermined high-efficiency region including a
maximum efficiency point in an efficiency characteristics of the
engine, when the compressor is driven in response to the
air-conditioning request; and a controller means that controls the
engine output such that the operating point of the engine is in the
high-efficiency region, if the increase in engine output is
determined to be allowed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims the benefit of
priority from Japanese Patent Application Nos. 2014-219636, filed
Oct. 28, 2014, and 2015-015116, filed Jan. 29, 2015. The entire
disclosures of each of the above applications are incorporated
herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure relates to a control apparatus that
includes a compressor for air-conditioning, and is used in a system
that enables adjustment of an operating point when an engine is
operated.
[0004] 2. Related Art
[0005] For example, a hybrid vehicle includes an engine and an
electric motor as power sources for running the vehicle. The hybrid
vehicle runs using power from at least one of the engine and the
electric motor. In the hybrid vehicle, there is an engine stop
period while the vehicle is running. Therefore, an electric
compressor is used as the compressor for air-conditioning. In this
case, an on-board battery is charged by a power generator, as
appropriate, by regenerative drive and engine drive. In addition,
when an air-conditioning request for air-conditioning to be
performed is issued, the battery supplies power to the compressor
based on the air-conditioning request. Thus, the compressor is
driven by power supply from the battery (refer to
JP-A-2000-232799).
[0006] In a configuration, such as that described above, in which
the compressor is driven by power supply from the battery,
deterioration of power consumption performance becomes a concern.
This is because battery power, which involves large
charge/discharge loss, is used. Power consumption is defined as,
for example, the amount of increase in fuel consumption per unit
power generated. In addition, while the compressor is driven,
feedback control is generally performed so as to make the actual
temperature inside a vehicle cabin match a target temperature.
However, in this configuration, energy efficiency related to
compressor-driving is not taken into consideration. Therefore, it
is thought that there is room for technical improvement.
SUMMARY
[0007] It is thus desired to provide a control apparatus that is
capable of improving power consumption performance.
[0008] An exemplary embodiment of the present disclosure provides a
control apparatus that is applied to a system including an engine
and a compressor for air-conditioning, and adjusts an operating
point of the engine when the engine is operated. The control
apparatus includes an allowed/not-allowed (allowed/prohibited)
determiner means and a controller means. The allowed/not-allowed
determiner means determines whether or not to allow increase in
engine output to drive a compressor based on an air-conditioning
request, based on the operating point of the engine before driving
of the compressor in relation to a predetermined high-efficiency
region including the maximum efficiency point, when the compressor
is driven in response to the air-conditioning request. The
controller means controls the engine output such that the operating
point of the engine is in the high-efficiency region, when a
determination is made to allow the increase in engine output.
[0009] In the present disclosure, when the compressor is driven
based on an air-conditioning request, whether or not to allow
increase in engine output to drive the compressor is determined
based on the operating point of the engine in relation to the
predetermined high-efficiency region including the maximum
efficiency point before driving of the compressor. When a
determination is made to allow the increase in engine output, the
engine output is controlled such that the operating point of the
engine is in the high-efficiency region. Therefore, reduction in
engine efficiency attributed to driving of the compressor can be
suppressed. In addition, from the perspective of the engine side,
the operating point of the engine can be brought into the
high-efficiency region from outside the high-efficiency region,
based on driving of the compressor. As a result, improvement in
power consumption performance can be actualized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the accompanying drawings:
[0011] FIG. 1 is a schematic diagram of an air-conditioning system
and an engine system according to a first embodiment;
[0012] FIG. 2 is a map of engine efficiency characteristics;
[0013] FIG. 3 is a flowchart of a process performed by an
air-conditioning electronic control unit (ECU);
[0014] FIG. 4 is a flowchart of a process performed by an engine
electronic control unit (ECU);
[0015] FIG. 5 is a diagram of an execution example of the processes
performed by the air-conditioning ECU and the engine ECU;
[0016] FIGS. 6A and 6B are diagrams of an operation example of the
air-conditioning system;
[0017] FIGS. 7A and 7B are diagrams of an operation example of an
air-conditioning system according to a second embodiment;
[0018] FIG. 8 is a flowchart of a pre-driving process according to
the second embodiment;
[0019] FIG. 9 is a flowchart of an abnormality determination
process according to a third embodiment;
[0020] FIGS. 10A and 10B are diagrams of an air-conditioning system
in a modified example; and
[0021] FIG. 11 is a diagram of an air-conditioning system in a
modified example.
DESCRIPTION OF EMBODIMENTS
First Embodiment
[0022] Embodiments of the present invention will be described with
reference to the drawings. In the descriptions below, the control
apparatus of the present invention is applied to a hybrid vehicle
that obtains driving force for running the vehicle from an engine
and an electric motor for running. The hybrid vehicle is capable of
switching between a running state (HV operation mode) in which the
hybrid vehicle runs by obtaining driving force from both the engine
and the electric motor for running, a running state (EV operation
mode) in which the engine is stopped and the hybrid vehicle runs by
obtaining driving force from only the electric motor for running,
and a running state in which the hybrid vehicle runs by obtaining
driving force from only the engine.
[0023] In FIG. 1, a vehicle 30 includes an engine 31, motors 32 and
33, a planetary gear unit 34, a drive shaft 35, a differential gear
36, a drive wheel 37, an inverter 39, and a battery 40. The motors
32 and 33 are configured by electrical power generators.
Specifically, the engine 31 is a known internal combustion engine
that uses gasoline, light oil, or the like as fuel. The engine 31
generates a desired engine output by combusting an air-fuel mixture
inside a combustion chamber. The air-fuel mixture is composed of
fuel and air, and is injected from a fuel injection valve. The
engine 31 and the motors 32 and 33 are drivably connected to each
other by the planetary gear unit 34. For example, an output shaft
of the engine 31 is connected to a carrier in the planetary gear
unit 34. The motor 32 is connected to a sun gear. The drive shaft
35 is connected to a link gear. In addition, the motor 33 is
connected to the drive shaft 35.
[0024] The inverter 39 is connected to the motors 32 and 33. When
the motors 32 and 33 are driven, power is supplied to each of the
motors 32 and 33 from the battery 40, via the inverter 39. In
addition, the motors 32 and 33 function as a power generator means.
When power is generated by the motors 32 and 33, the generated
power is supplied to the battery 40 via the inverter 39. The
battery 40 is charged by the supplied power. Specifically, during
deceleration of the vehicle 30, the motor 33 performs regenerative
power generation. When a charge request is issued at times other
than during regenerative power generation, the motor 32 performs
power generation by the engine 31 being driven.
[0025] In addition, the vehicle 30 includes an engine electronic
control unit (ECU) 21 that controls the engine 31, and a motor ECU
22 that controls the motors 32 and 33 and the inverter 39. The ECUs
21 and 22 are each mainly configured by a known microcomputer that
is composed of a central processing unit (CPU), a read-only memory
(ROM), a random access memory (RAM), and the like. The basic
configuration of control performed by the ECUs 21 and 22 is well
known. Therefore, a detailed description thereof is omitted.
However, a brief description is as follows.
[0026] The engine ECU 21 obtains engine rotation speed, engine
load, water temperature, air-fuel ratio, and the like as
information indicating an engine operating state. The engine ECU 21
controls the fuel injection amount, ignition timing, air amount,
and the like, as appropriate, based on the obtained information. In
addition, the motor ECU 22 controls driving of the motors 32 and 33
in response to a motor drive request, and also controls
charging/discharging of the battery 40. Regarding charging of the
battery 40, the motor ECU 22 calculates a state of charge (SOC) of
the battery 40 based on terminal voltage, charge/discharge current,
and the like of the battery 40, and charges the battery 40, as
appropriate, based on the SOC.
[0027] In addition, FIG. 1 shows an on-board air-conditioning
system. An air-conditioning system 10 is configured to include a
compressor 11, a condenser 12, a receiver 14, a thermal expansion
valve 16, an evaporator 18, a fan 19, and the like. The compressor
11 intakes and discharges a refrigerant to circulate the
refrigerant in a refrigeration cycle 10a. The compressor 11 is an
electric compressor that is driven by power supply received from
the battery 40 or the like. In addition, the compressor 11 is
provided with a variable capacity function. The refrigerant
discharge capacity of the compressor 11 can be continuously
variably set by an energization operation of an electromagnetically
driven control valve.
[0028] The evaporator 18 vaporizes some or all of the refrigerant
by heat exchange between the air blown from the fan 19 and the
refrigerant, which is in a mist state. The fan 19 is rotatably
driven by a direct current (DC) motor or the like. As a result, the
air blown from the fan 19 is cooled, and the cooled air is sent to
the vehicle cabin, via an air outlet (not shown) provided inside
the vehicle cabin. The vehicle cabin interior is thereby
cooled.
[0029] According to the present embodiment, the evaporator 18 is
provided with a cold storage function. That is, a cold storage
material 18a, such as paraffin, is enclosed within the evaporator
18. The cold storage material 18a stores surplus heat for cooling
that is generated in the refrigeration cycle 10a when the
compressor 11 is driven. The heat stored in the cold storage
material 18a can be used for cooling while the compressor 11 is
stopped.
[0030] Specifically, heat of the refrigerant is stored in the
evaporator 18 by heat exchange between the refrigerant that is
supplied to the evaporator 18 by the compressor 11 being driven,
and the cold storage material 18a. Subsequently, when the
compressor 11 is stopped, heat is exchanged between the air blown
from the fan 19 and the cold storage material 18a, and the blown
air is thereby cooled. The cooled air is then sent to the vehicle
cabin. As a result, the vehicle cabin interior is cooled even when
the compressor 11 is stopped. The refrigerant that flows out of the
evaporator 18 is taken in through an intake opening of the
compressor 11.
[0031] An air-conditioning ECU 23 that controls the
air-conditioning system 10 is mainly configured by a known
microcomputer that is composed of a CPU, a ROM, a RAM, and the
like. Various command signals are inputted into the
air-conditioning ECU 23. These command signals serve as commands to
drive the compressor 11 so as to cool the vehicle cabin interior.
For example, signals are inputted from an A/C switch (not shown), a
temperature sensor (evaporator sensor) that detects the temperature
of the air that has been heat-exchanged in the evaporator 18, and
an external temperature sensor that detects the outside temperature
equivalent to the temperature of the air before being
heat-exchanged in the evaporator 18.
[0032] The air-conditioning ECU 23 performs cooling control of the
vehicle cabin interior (controls driving of the compressor 11) and
the like by running various control programs stored in the ROM, in
response to input of the foregoing signals. That is, in a state in
which the A/C switch is turned ON, when the temperature inside the
vehicle cabin exceeds a target value thereof by a predetermined
amount or more, the air-conditioning ECU 23 determines that an
air-conditioning request to perform cooling is issued. The
air-conditioning ECU 23 outputs a request signal, as needed, to
drive the compressor 11 so as to circulate the refrigerant in the
refrigeration cycle 10a.
[0033] The ECUs 21 to 23 are electrically connected and capable of
bi-directional communication. Therefore, based on detection signals
or operating signals inputted into either of the ECUs 21 and 23,
driving of various apparatuses connected to the output side of the
other ECU can be controlled. For example, the engine ECU 21 is
capable of receiving a request signal outputted from the
air-conditioning ECU 23.
[0034] According to the present embodiment, when the compressor 11
is driven based on an air-conditioning request, in addition to the
compressor 11 being driven by power supplied from the battery 40,
the compressor 11 can also be driven by receiving power generated
by the motor 32. In other words, when the compressor 11 is driven
in response to the air-conditioning request, the motor 23 performs
surplus power generation by the engine 31 being driven. The power
resulting from the surplus power generation (referred to,
hereafter, as surplus power) is then used to drive the compressor
11. That is, in surplus power generation, surplus power that is not
used as the driving force for running the vehicle 30 is outputted.
In this case, the amount of output of the surplus power is added to
the engine output at the start of driving of the compressor 11, and
operation of the engine 31 thereby is controlled.
[0035] In addition, according to the present embodiment, the engine
ECU 21 is capable of adjusting the operating point during operation
of the engine 31. When the compressor 11 is driven based on an
air-conditioning request, the engine ECU 21 determines whether or
not to allow increase in engine output (the surplus power
generation by the motor 32 by the engine 31 being driven) to drive
the compressor 11 in response to the air-conditioning request,
based on where the engine operating point is before driving of the
compressor 11, in relation to a predetermined high-efficiency
region that includes the maximum efficiency point of engine
efficiency characteristics. In other words, the engine ECU 21
determines whether or not to allow increase in engine output to
drive the compressor 11 in response to the air-conditioning
request, based on the operating point of the engine before driving
of the compressor 11 in relation to the predetermined
high-efficiency region including a maximum efficiency point. In
addition, when determined that the increase in engine output is
allowed, the engine ECU 21 controls engine output such that the
operating point of the engine is in the high-efficiency region.
[0036] Here, FIG. 2 shows a map of engine efficiency
characteristics. In FIG. 2, a performance curve (torque curve) of
the engine 31 is prescribed with the engine rotation speed (NE) and
engine torque as parameters. The magnitude of engine efficiency in
each region is also prescribed. A region in which engine efficiency
is the same is indicated by a contour line. Engine efficiency
characteristics are also characteristics indicating an equivalent
fuel consumption curve. In the map, a high-efficiency region F0 is
shown as a region including the maximum efficiency point. A
relationship is prescribed in which engine efficiency decreases as
the operating point becomes farther from the high-efficiency region
F0.
[0037] For example, when the engine operating point is point A that
is further towards the low NE (engine rotation speed) side than the
high-efficiency region F0, as a result of the increase in engine
output (the surplus power generation by the motor 32 by the engine
31 being driven) being performed, the engine operating point nears
the high-efficiency region F0. The engine 31 can be operated within
the high-efficiency region F0. In this case, the desired driving
power can be supplied to the compressor 11 while operating the
engine 31 at high efficiency (low fuel consumption). According to
the present embodiment, in particular, because the cold
storage-type evaporator 18 is used in the air-conditioning system
10, the increase in engine output to drive the compressor 11 can be
relatively large. The engine operating point can be more easily set
in the high-efficiency region F0.
[0038] When the engine operating point is point B within the
high-efficiency region F0, or point C that is further towards the
high NE side than the high-efficiency region F0, reduced engine
efficiency resulting from the increase in engine output becomes a
concern. Therefore, engine output is not increased.
[0039] In addition, in a state in which the compressor 11 is being
driven as a result of the increase in engine output (the surplus
power generation by the motor 32 by the engine 31 being driven),
the engine operating point is in the high-efficiency region F0 at
the initial start of driving of the compressor 11. However, there
is concern that the engine operating point may shift further
towards the high NE side than the high-efficiency region F0, due to
various fluctuating factors such as fluctuations in the vehicle
running state and the engine operating state. Therefore, according
to the present embodiment, in a state in which the compressor 11 is
being driven, whether or not the engine operating point has shifted
further towards the high NE side than the high-efficiency region F0
is determined. Engine output is decreased when the shift
occurs.
[0040] Next, a process performed by the air-conditioning ECU 23 and
a process performed by the engine ECU 21 will be described with
reference to FIG. 3 and FIG. 4. The following processes are
repeatedly performed by the air-conditioning ECU 23 and the engine
ECU 21 when an ignition switch (not shown) is turned ON.
[0041] First, the process performed by the air-conditioning ECU 23
will be described with reference to FIG. 3. First, the
air-conditioning ECU 23 determines whether or not an
air-conditioning request to perform cooling has been issued (step
S11). When determined that an air-conditioning request is issued,
the air-conditioning ECU 23 determines whether or not the
compressor 11 is in a stop state (step S12).
[0042] When determined that the compressor 11 is in the stop state
(that the compressor 11 has stopped), the air-conditioning ECU 23
determines whether or not output conditions for a request signal
are met (step S13). At this time, the air-conditioning ECU 23
determines that the output conditions for the request signal are
met when the temperature inside the vehicle cabin is higher than
the target value by a predetermined amount, and the remaining
cooling capability due to cold storage in the evaporator 18 is zero
or near zero. The remaining cooling capability of the evaporator 18
is preferably determined based on, for example, the evaporator
temperature detected by the evaporator sensor. When the evaporator
temperature is a predetermined temperature or higher, the
air-conditioning ECU 23 determines that the compressor 11 needs to
be driven and determines that the output conditions for the request
signal are met. When the evaporator temperature is lower than the
predetermined temperature, the air-conditioning ECU 23 determines
that the compressor 11 does not need to be driven and determines
that the output conditions for the request signal are not met.
Alternatively, the remaining cooling capability of the evaporator
18 may be determined based on the amount of time elapsed from when
driving of the compressor 11 (refrigerant circulation) is
stopped.
[0043] When determined YES at step S13, the air-conditioning ECU 23
outputs a request signal (step S14). The request signal includes
information, such as a requested driving output PD required to
drive the compressor 11. According to the present embodiment, the
amount of power that enables driving at the highest efficiency is
prescribed as the requested driving output PD, taking into
consideration the efficiency of the compressor 11 (for example,
PD=4.0 kW).
[0044] When determined that the compressor 11 is in a driving state
at step S12, the air-conditioning ECU 23 determines whether or not
a stop condition for the compressor 11 is met (step S15). For
example, the air-conditioning ECU 23 may determine that the stop
condition is met upon the elapse of a predetermined amount of time
from the start of driving of the compressor 11. The predetermined
amount of time is preferably determined based on the cold storage
capability of the evaporator 18. For example, the predetermined
amount of time is increased as the cold storage capability
increases. When determined that the stop condition for the
compressor 11 is met, the air-conditioning ECU 23 stops output of
the request signal (step S16). The air-conditioning ECU 23 ends the
process when determined that the stop condition of the compressor
11 is not met at step S15.
[0045] Next, the process performed by the engine ECU 21 will be
described with reference to FIG. 4. In FIG. 4, first, the engine
ECU 21 determines whether or not a request signal has been received
from the air-conditioning ECU 23 (step S21). When determined that a
request signal is not received, the engine ECU 21 ends the process.
When determined that a request signal is received, the engine ECU
21 determines whether or not the current state is before the start
of driving of the compressor 11 in response to the request signal
(step S22). When determined that a request signal is received and
the compressor 11 is not yet driven, the engine ECU 21 performs a
pre-driving process (steps S23 to S27). When determined that a
request signal is received and the compressor 11 is being driven,
the engine ECU 21 performs a post driving-start process (steps S28
to S33).
[0046] As the pre-driving process, first, the engine ECU 21
determines whether or not engine efficiency will improve as a
result of surplus power generation being performed by the motor 32
by the engine 13 being driven (step S23). Specifically, the engine
ECU 21 determines whether or not the current engine operating point
is further towards the low NE side than the high-efficiency region
F0. When determined that the current engine operating point is on
the low NE side, the engine ECU 21 determines that engine
efficiency will improve. In other words, the engine ECU 21
determines YES at step S23 when determined that the engine
operating point will become closer to the high-efficiency region F0
as a result of surplus power generation by the motor 32. The engine
ECU 21 thereby allows increase in engine output. When determined NO
at step S23, the engine ECU 21 ends the process. When determined NO
at step S23, the compressor 11 cannot be driven using surplus
power. Therefore, the compressor 11 can be driven by power supply
from the battery 40.
[0047] When determined YES at step S23, the engine ECU 23
calculates an increasable output by which engine output can be
increased without the engine operating point exceeding the
high-efficiency region F0, based on the current engine operating
point (step S24). The increasable output is calculated as a smaller
power value as the current engine operating point becomes closer to
the high-efficiency region F0, and is calculated as a larger value
as the current engine operating point becomes farther from the
high-efficiency region F0.
[0048] Subsequently, the engine ECU 21 determines whether or not
the requested driving output PD for the compressor 11 is greater
than the increasable output (step S25). When determined that the
requested driving output PD for the compressor 11 is greater than
the increasable output, the engine ECU 21 adds the amount of
increase corresponding to the increasable output to the current
engine output (step S26). When determined that the requested
driving output PD for the compressor 11 is less than the
increasable output, the engine ECU 21 adds the amount of increase
corresponding to the requested driving output. PD for the
compressor 11 to the current engine output (step S27).
[0049] In other words, at steps S25 to S27, the smaller of the
requested driving output PD for the compressor 11 and the
increasable output is added to the current engine output. As a
result, surplus power generation by the motor 32 can be performed
while preventing the post-addition engine output from leaving the
high-efficiency region F0.
[0050] At step S26, because the increasable output that is less
than the requested driving output PD is added to the engine output,
the engine output is insufficient for the requested driving output
PD. However, the insufficient amount may be supplemented by power
supply from the battery 40.
[0051] When the addition to the engine output is performed as
described above, the engine ECU 21 increases intake air amount and
fuel injection amount in an output control process (not shown). As
a result, the engine output is controlled such that the operating
point of the engine 31 is in the high-efficiency region F0. The
operating point of the engine 31 is not necessarily required to be
in the high-efficiency region F0. All that is required is that the
engine operating point be shifted closer to the high-efficiency
region F0.
[0052] In addition, as the post driving-start process, first, the
engine ECU 21 determines whether or not the engine operating point
will become closer to the high-efficiency region F0 when the amount
of increase in engine output to drive the compressor 11 is
decreased (step S28). That is, it is premised that the engine
operating point may shift further towards the high NE side than the
high-efficiency region F0 as a result of various fluctuating
factors. The engine ECU 21 determines whether or not efficiency
improvement is needed as a result of the shift from the
high-efficiency region F0. When determined NO at step S28, the
engine ECU 21 ends the process.
[0053] When determined YES at step S28, the engine ECU 21
determines whether or not the current air-conditioning request can
be fulfilled, or in other words, whether or not air-conditioning of
the vehicle cabin interior can be continued, even when the amount
of increase in engine output is decreased (step S29). When
determined NO at step S29, the engine ECU 21 ends the process.
[0054] When determined YES at step S29, the engine ECU 21
calculates a decreasable output by which engine output can be
decreased without the engine operating point exceeding the
high-efficiency region F0, based on the current engine operating
point (the operating point when the compressor 11 is in the driving
state) (step S30). The decreasable output is calculated as a larger
power value as the current engine operating point shifts more
towards the high NE side from the high-efficiency region F0.
[0055] Subsequently, the engine ECU 21 determines whether or not
the requested driving output PD for the compressor 11 is greater
than the decreasable output (step S31). When determined that the
requested driving output PD for the compressor 11 is greater than
the decreasable output, the engine ECU 21 subtracts the decreasable
output from the current engine output (step S32). When determined
that the requested driving output PD of the compressor 11 is less
than the decreasable output, the engine ECU 21 subtracts the
requested driving output PD of the compressor 11 from the current
engine output (step S33).
[0056] In other words, at steps S31 to S33, the smaller of the
requested driving output PD for the compressor 11 and the
decreasable output is subtracted from the current engine output. As
a result, surplus power generation by the motor 32 can be performed
while preventing the post-subtraction engine output from leaving
the high-efficiency region F0.
[0057] When the amount of the surplus power added at the start of
driving of the compressor 11 is reduced as a result of the
processes at steps S32 and S33, the engine output is insufficient
for the requested driving output PD. However, the insufficient
amount may be supplemented by power supply from the battery 40.
[0058] Next, an execution example of the processes described above
will be described with reference to FIG. 5. In the present example,
it is premised that the engine operating point is further towards
the low NE side than the high-efficiency region F0 (such as point A
in FIG. 2) when the compressor 11 is driven based on an
air-conditioning request.
[0059] In FIG. 5, an air-conditioning request is issued at time t1.
The compressor 11 is driven thereafter, as needed. First, at time
t1, the request signal to drive the compressor 11 is outputted from
the air-conditioning ECU 23 to the engine ECU 21. At this time,
because the engine operating point is further towards the low NE
side than the high-efficiency region F0, as described above, the
engine ECU 21 determines that engine efficiency will be improved by
surplus power generation. The engine ECU 21 allows increase in
engine output. In FIG. 5, a case in which a requested driving
output PD is equal to or less than an increasable output
(PD.ltoreq.increasable output) is premised. Therefore, power equal
to the requested driving output PD is supplied to the compressor 11
from the motor 32. The compressor 11 is driven by the supplied
power.
[0060] When surplus power generation by the motor 32 is performed,
engine output is increased such that the engine operating point is
in the high-efficiency region F0. At this time, if the requested
driving output PD is more than increasable output
(PD>increasable output), the amount of increase in engine output
is limited by the increasable output.
[0061] In this case, the compressor 11 is driven by driving power
that is greater than the driving power (feedback amount) calculated
based on the deviation between the vehicle cabin temperature and
the target temperature. For example, whereas driving power of about
1 kW is required based on the feedback amount, a larger driving
power of about 4 kW is supplied.
[0062] Power supply to the compressor 11 is performed during the
period of time t1 to t2 during which the request signal is
generated. The period of time t1 to t2 is a cold storage period
during which cold storage is performed in the evaporator 18. The
surplus amount of heat generated by the driving of the compressor
11 is cold-stored in the cold storage material 18a.
[0063] Subsequently, at time t2, output of the request signal is
stopped, and driving of the compressor 11 is stopped in
accompaniment. At time t2, surplus power generation by the motor 32
(addition to engine output) is stopped. Then, during the cold
release period following time t2, air conditioning is continued
using the cold storage of the cold storage material 18a while the
compressor 11 is in a stop state.
[0064] Then, at time t3, when the remaining cooling capability by
cold storage in the evaporator 18 has decreased to zero or near
zero, the request signal is again outputted from the air
conditioning ECU 23. As a result, in a manner similar to that at
time t1, increase in engine output is allowed and driving of the
compressor 11 by surplus power generation is started. Thereafter,
driving of the compressor 11 by surplus power generation by the
motor 32 is intermittently performed in a state in which the air
conditioning request is being issued.
[0065] Here, when engine output increases as a result of
fluctuations in the vehicle running state and the like, and the
engine operating point shifts, during driving of the compressor 11
by surplus power generation, the process to reduce the amount of
increase in engine output (the amount of surplus power generation)
is performed. That is, at time t11 in FIG. 5, the requested driving
output PD is subtracted from the current engine output. In this
case, driving of the compressor 11 by surplus power generation
cannot be continued. However, the state in which the engine
operating point is in the high-efficiency region F0 is
maintained.
[0066] Following time t11, the engine operating point is in the
high-efficiency region F0 in a state in which surplus power
generation is not performed. No further efficiency improvement can
be expected. Therefore, driving of the compressor 11 by the surplus
power generation by the motor 32 is not performed.
[0067] As a result of the foregoing, the following excellent
effects are achieved.
[0068] When the compressor for air conditioning is directly driven
by the generated power of a motor, improvement in power consumption
performance can be expected, compared to when the compressor is
driven by power supplied from a battery. A reason for this is that
charge/discharge loss increases in a battery during power use.
However, when power generation by a motor (that is, power supply to
the compressor) is performed by the engine being driven without
taking into consideration engine efficiency, there is concern that
not much improvement in power consumption performance can be
expected.
[0069] In this regard, in the above-described configuration, when
the compressor 11 is driven based on an air-conditioning request,
whether or not to allow increase in engine output to drive the
compressor 11 is determined based on the operating point of the
engine 31 in relation to the high-efficiency region F0 including
the high efficiency point before the compressor 11 is driven. When
a determination is made to allow increase in engine output, the
engine output is controlled such that the operating point of the
engine 31 is in the high-efficiency region F0.
[0070] Therefore, reduction in engine efficiency attributed to
driving of the compressor 11 can be suppressed. In addition, from
the perspective of the engine 31 side, the operating point of the
engine 31 can be brought into the high-efficiency region F0 from
outside the high-efficiency region F0, based on driving of the
compressor 11. Therefore, as a result, improvement in power
consumption performance can be actualized.
[0071] When the compressor 11 is driven in response to an air
conditioning request, a determination to allow increase in engine
output is made when the engine operating point becomes closer to
the high-efficiency region F0 as a result of surplus power
generation by the motor 32. In this case, determination of the
suitability of surplus power generation by the motor 32 can be
favorably performed, and can contribute to improving power
consumption performance.
[0072] As a result of the above-described configuration, when the
requested driving output for the compressor 11 is greater than the
increasable output, the amount of increase corresponding to the
increasable output, rather than the amount of increase
corresponding to the requested driving output for the compressor
11, is added to the current engine output. Therefore, the engine
operating point after the increase in engine output exceeding the
high-efficiency region F0 can be suppressed.
[0073] As a result of the above-described configuration, when the
requested driving output for the compressor 11 is less than the
increasable output, the amount of increase corresponding to the
requested driving output for the compressor 11 is added to the
current engine output. Therefore, increase in engine output
appropriate for the request signal to drive the compressor 11 can
be suitably performed. As a result, control of engine output
appropriate for the request signal can be suitably performed, while
maintaining the engine operating point after increase in engine
output within the high-efficiency region.
[0074] When surplus power generation by the motor 32 is performed,
the requested driving output for the compressor 11 is power
enabling the compressor 11 to be driven in a predetermined high
efficiency state. In this case, driving of the compressor 11 can be
performed taking into consideration efficiency on the compressor 11
side, as well.
[0075] Increase in engine output is performed intermittently with
pauses between increases, rather than the engine output being
continuously increased. Therefore, optimization of engine
efficiency can be achieved while suppressing excessive supply of
power to the compressor 11.
[0076] When the cold storage material 18a is provided that stores
heat from the refrigerant that is circulated by the compressor 11
being driven, the cold release period of the cold storage material
18a can be increased when driving of the compressor 11 is
intermittently performed by surplus power generation by the motor
32, when the compressor 11 is driven based on an air-conditioning
request. In this case, a more suitable engine control can be
actualized without excessively introducing surplus power for
air-conditioning.
[0077] In a state in which the compressor 11 is being driven by
surplus power from the motor 32, a determination is made regarding
whether or not the engine operating point will be closer to the
high-efficiency region F0 as a result of the amount of increase in
engine output for driving the compressor 11 being reduced. When the
engine operating point is determined to become closer to the
high-efficiency region F0, the engine output is decreased. In this
case, even when the engine operating point shifts to a state in
which the engine output is controlled by surplus power from the
motor 32, the engine operating point can be maintained within the
high frequency region F0.
[0078] As a result of the above-described configuration, when the
requested driving output for the compressor 11 is greater than a
decreasable output, the amount of decrease corresponding to the
decreasable output is subtracted from the current engine output,
rather than the amount of decrease corresponding to the requested
driving output for the compressor 11. Therefore, the engine
operating point after decrease in engine output exceeding the
high-efficiency region can be suppressed.
[0079] As a result of the above-described configuration, when the
requested driving output for the compressor 11 is less than the
decreasable output, the amount of decrease corresponding to the
requested drive output of the compressor 11 is subtracted from the
current engine output. Therefore, decrease in engine output
appropriate for the request signal can be suitably performed. As a
result, control of engine output appropriate for the request signal
can be suitably performed while maintaining the engine operating
point after decrease in engine output within the high-efficiency
region F0.
[0080] In a state in which the compressor 11 is being driven by
surplus power from the motor 32, when a determination is made that
the engine operating point becomes closer to the high-efficiency
region F0 as a result of the amount of increase in engine output
being reduced, and the air-conditioning request is fulfilled, the
engine output is decreased. As a result, the air-conditioning state
can be maintained while maintaining the engine operating point
within the high-efficiency region F0.
Second Embodiment
[0081] In the description above, in the pre-driving process at
steps S23 to S27 in FIG. 4, the smaller of the requested driving
output PD for the compressor 11 and the increasable output is added
to the current engine output. Surplus power generation by the motor
32 is thereby controlled such that the post-addition engine output
does not leave the high-efficiency region. However, when the
increasable output is greater than the requested driving output PD,
the amount added to the engine output is limited by the requested
driving output PD. Therefore, the improvement in engine efficiency
may be limited in a state in which the engine operating point can
be brought even closer to the maximum efficiency point.
[0082] For example, when the engine operating point is at point A
that is further towards the low NE side than the high-efficiency
region F0, as shown in FIG. 6B, the increasable output by which
engine output can be increased without the engine operating point
exceeding the high-efficiency region F0 is N1 (kW) and the
requested driving output PD for the compressor 11 is N2 (kW) that
is less than the increasable output N1, as shown in FIG. 6A. In
this case, when the amount of increase corresponding to the
increasable output N1 is added to the current engine output, the
engine operating point can be improved so as to be in the
high-efficiency region F0. However, when the amount of increase
corresponding to the requested driving output PD is added to the
current engine output, rising of the engine operating point is
limited to an efficiency point D1 that is below the high-efficiency
region F0.
[0083] When the surplus power outputted as a result of the surplus
power generation by the motor 32 by the engine 31 being driven can
be supplied to another apparatus (load), the engine operating point
can be further improved by taking advantage of the supply of
surplus power to the other apparatus. According to the present
embodiment, surplus power can be supplied to the battery 40 as
charging power. Taking advantage of this feature, the amount of
increase corresponding to chargeable power PD1, which is power with
which the battery 40 can be charged, can be further added to the
engine output. Engine efficiency can be further improved. The
chargeable power PD1 is calculated by the motor ECU 22 based on
battery characteristics, such as the charging state (SOC) of the
battery 40 and the battery temperature.
[0084] For example, when the engine operating point is further
towards the low NE side than the high frequency region F0, as shown
in FIG. 7B, the chargeable power PD1 of the battery 40 is added to
the requested driving output PD required for driving the compressor
11, as shown in FIG. 7A. In this case, compared to the instance in
FIG. 6B, in FIG. 7B, the engine operating point can be elevated to
an efficiency point D2 (such as the maximum efficiency point)
within the high-efficiency region.
[0085] It is assumed that the total value (referred to, hereafter,
as a total requested driving output) of the chargeable power PD1
and the requested driving output PD may be greater than the
increasable output N1. In this case, the amount of increase
corresponding to the increasable output N1 is added to the engine
output. In this case, engine efficiency can be improved while
suppressing a state in which the engine operating point exceeds the
high-efficiency region F0.
[0086] In addition, when surplus power can be supplied to a
plurality of apparatuses including the compressor 11, the supply
destination of the surplus power is preferably determined based on
priority level for the supply of surplus power. For example,
according to the present embodiment, when surplus power can be
supplied to both the compressor 11 and the battery 40, the surplus
power is preferentially supplied to the compressor 11 which has
high power conversion efficiency. When surplus power is greater
than the requested driving output, and the amount of surplus power
supplied to the compressor 11 becomes excessive, the remaining
surplus power is supplied to the battery 40 as charging power. In
this way, when the supply destination of surplus power is
determined based on priority level for power supply, engine
efficiency can be improved while protecting air-conditioning
performance and the battery 40.
[0087] Next, a pre-driving process according to the second
embodiment performed by the engine ECU 21 will be described with
reference to FIG. 8. The present process is performed when the
engine ECU 21 determines YES at steps S21 and S22 in the process in
FIG. 4, described above. In addition, in the description hereafter,
detailed descriptions of processes that are the same as the
processes in FIG. 4 are omitted.
[0088] As the pre-drive process, first, the engine ECU 21
determines whether or not engine efficiency can be improve as a
result of surplus power generation being performed by the motor 32
by the engine 13 being driven (step S41). When determined that
engine efficiency cannot be improved, the engine ECU 21 ends the
process. When determined that engine efficiency can be improved,
the engine ECU 21 calculates the increasable output (step S42).
Next, the engine ECU 21 determines whether or not the total
requested driving output is greater than the increasable output
(step S43).
[0089] When determined that the total requested driving output is
greater than the increasable output, the engine ECU 21 adds the
amount of increase corresponding to the increasable output to the
current engine output (step S44). Then, the engine ECU 21 supplies
the surplus power generated by the surplus power generation at step
S44 to the compressor 11 (step S45). Next, the engine ECU 21
determines whether or not the surplus power is greater than a
requested driving power PI (step S46). When determined YES at step
S46, the engine ECU 21 supplies the surplus from the power supply
to the compressor 11 (surplus power-requested driving power PI) to
the battery 40 (step S47). When determined NO at step S46, the
engine ECU 21 ends the process.
[0090] When determined that the total requested driving output is
less than the increasable output at step S43, the engine ECU 21
adds the amount of increase corresponding to the total requested
driving output to the current engine output (step S48). The engine
ECU 21 then performs the processes at steps S45 to S47.
[0091] As a result of the foregoing, the following excellent
effects are achieved.
[0092] The sum of the requested driving output for the compressor
11 and the requested charging power for the battery 40 is the total
requested driving output. When the total requested driving output
is greater than the increasable output, the amount of increase
corresponding to the increasable output is added to the current
engine output. Therefore, the engine operating point can be
elevated towards the high-efficiency region F0 side as a result of
increase in engine output based on the increasable output, while
suppressing a state in which the engine operating point after the
increase in engine output exceeds the high-efficiency region
F0.
[0093] The sum of the requested driving output for the compressor
11 and the requested charging power for the battery 40 is the total
requested driving output. When the total requested driving output
is less than the increasable output, the amount of increase
corresponding to the total requested driving output is added to the
current engine output. Therefore, the engine operating point can be
further elevated towards the high-efficiency region F0 side
compared to when the engine output is increased only by the
requested driving output for the compressor 11, while suppressing a
state in which the engine operating point after the increase in
engine output exceeds the high-efficiency region F0.
[0094] When the surplus power generated by surplus power generation
can be supplied to both the compressor 11 and the battery 40, the
surplus power is supplied to the compressor 11 or the battery 40
that has a higher priority level for power supply. Therefore,
engine efficiency can be improved while protecting air-conditioning
performance of the air-conditioning system 10 and protecting the
battery 40.
[0095] When the amount of surplus power supplied to a load (the
compressor 11 or the battery 40) having a high priority level for
power supply exceeds an allowable amount, the remaining surplus
power is supplied to another load. Therefore, engine efficiency can
be improved while making use of surplus power.
[0096] When surplus power can be supplied to both the compressor 11
and the battery 40, the surplus power is preferentially supplied to
the compressor 11 which has a high power conversion efficiency.
Therefore, engine efficiency can be improved while improving system
efficiency.
Third Embodiment
[0097] When the compressor 11 cannot be driven by surplus power,
such as when disconnection or another malfunction occurs in the
compressor 11, a problem caused by excessive surplus power
generation may occur when the total requested driving output, set
based on the requested driving output PD for the compressor 11 and
the chargeable power PD1 of the battery 40, is set as the upper
limit value of the amount of increase in engine output by surplus
power generation. Therefore, when an abnormal state in which the
compressor 11 cannot be driven by surplus power occurs, the upper
limit value of the amount of increase in engine output may be set
to the chargeable power PD1 of the battery 40.
[0098] For example, in the flowchart of a modified example in FIG.
9, the engine ECU 21 determines whether or not there is no
abnormality in the compressor 11 (step S51). In the present
process, the engine ECU 21 can make the determination based on
detected values for voltage and current of the compressor 11, and
the like.
[0099] When determined that there is no abnormality at step S51,
the engine ECU 21 sets the upper limit value of the amount of
increase in engine output to the total requested driving output,
which is the total value of the requested driving output PD for the
compressor 11 and the chargeable power PD1 of the battery 40 (step
S52). When determined that there is an abnormality at step S51, the
engine ECU 21 sets the upper limit value of the amount of increase
in engine output to the chargeable power PD1 of the battery 40
(step S53). As a result, even when surplus power cannot be supplied
to the compressor 11, engine efficiency can be improved through use
of the chargeable power of the battery 40.
Other Embodiments
[0100] The present invention is not limited to the descriptions
above. The present invention may also be carried out as described
below. Configurations in the descriptions below that are the same
as the configurations described above are given the same reference
numbers. Detailed descriptions thereof are omitted. In addition,
the embodiments described above can be combined with the other
embodiments described below.
[0101] According to the above-described first embodiment, when the
motor 32 performs surplus power generation, the requested driving
output PD for the compressor 11 is the amount of power enabling the
compressor 11 to be driven at the highest efficiency. However, this
may be changed. For example, the requested driving output PD for
the compressor 11 may be variably set based on the difference
between the engine operating point before the start of driving of
the compressor 11 and the high-efficiency region F0. In this case,
the requested driving output PD increases as the difference between
the engine operating point and the high-efficiency region F0
increases.
[0102] According to the above-described first embodiment, a
following configuration is possible. When the request signal to
drive the compressor 11 is outputted at step S21 in FIG. 4, whether
or not the engine 31 is in a state of operation may be determined.
When the engine 31 is stopped, driving of the compressor 11 by
surplus power generation may not be performed.
[0103] According to the above-described first embodiment, surplus
power generation may be performed in the process in FIG. 4 such
that, when the request signal from the air-conditioning ECU 23 is
issued in the process in FIG. 3, the operating point of the engine
31 is in the high-efficiency region F0 regardless of the driving
amount of the compressor 11 based on the request signal. In this
case, surplus power may be used to charge the battery 40.
[0104] According to the above-described first embodiment, the
amount of power enabling the compressor 11 to be driven at the
highest efficiency is prescribed as the requested driving output
PD, taking into consideration the efficiency of the compressor 11.
However, the requested driving output PD may also be prescribed as
being a value that enables the compressor 11 to be driven in a
predetermined state of high efficiency. In addition, the requested
driving output PD may be variably set depending on the heat storage
state of the cold storage material 18a.
[0105] According to the above-described second embodiment, an
example is given in which, when surplus power can be supplied to
both the compressor 11 and the battery 40, the surplus power is
preferentially supplied to the compressor 11. However, in the
process in FIG. 8, the apparatus (load) to be preferentially
supplied the surplus power can be determined, based on the priority
levels for power supply of the compressor 11 and the battery
40.
[0106] For example, the priority levels for power supply of the
compressor 11 and the battery 40 can be determined based on vehicle
cabin temperature and battery characteristics.
[0107] Specifically, when the vehicle cabin temperature is high,
the surplus power is preferentially supplied to the compressor 11
to prioritize to the cooling function. Meanwhile, when the SOC of
the battery 40 is low, the surplus power is preferentially supplied
to the battery 40 to protect the battery 40. When the vehicle cabin
temperature is high and the SOC of the battery 40 is low, the
surplus power is preferentially supplied to the battery 40 to
protect the battery 40. In addition, when the temperature of the
battery 40 is high, the surplus power is preferentially supplied to
the compressor 11 to protect the battery 40.
[0108] According to the above-described second embodiment, an
example is given in which, in the process in FIG. 8, surplus power
is supplied to an apparatus having a high priority level for power
supply. The remaining surplus power is supplied to another
apparatus. In addition, a distribution ratio for surplus power to
each apparatus may be set based on the priority levels. For
example, the ratio of surplus power supplied to the compressor 11
and the battery 40 is set based on the priority levels.
Specifically, the ratio of surplus power supplied to the compressor
11 is increased by setting the compressor 11 to a higher priority
level as the vehicle cabin temperature increases. The ratio of
power supply supplied to the battery 40 is increased by setting the
battery 40 to a higher priority level as the SOC of the battery 40
decreases.
[0109] According to the above-described second embodiment, when
surplus power can be supplied to both the compressor 11 and the
battery 40, the surplus power may be supplied to the compressor 11
which has a high power conversion efficiency, without taking into
consideration the priority level.
[0110] According to the above-described second embodiment, the
total requested driving output may be set to the total value of the
requested driving output PD for the compressor 11, the chargeable
power PD1 of the battery 40, and charge loss of the battery 40. In
this case, the surplus power that is outputted using surplus power
generation can be further increased, and engine efficiency can be
more easily improved.
[0111] According to the above-described second embodiment, the
total requested driving output may be set taking into consideration
the amount of cold storage in the evaporator 18. In this case,
engine output for surplus power generation can be further
increased.
[0112] According to the above-described second embodiment, an
example is given in which the surplus power is supplied to the
compressor 11 and the battery 40. However, when another apparatus
(load) that can be supplied surplus power is mounted in the vehicle
30, the upper limit of the amount of increase in engine output may
be set taking into consideration the amount of surplus power
supplied to this apparatus.
[0113] In the descriptions above, when the charging request for
charging of the battery 40 is outputted as a result of the SOC of
the battery 40 decreasing below a predetermined level, when the
operating point of the engine 31 enters the high-efficiency region
F0 as a result of the amount for driving the compressor 11 being
added, the motor 32 may perform power generation with the addition
of the amount for driving the compressor 11. When cold storage for
the compressor 11 is performed using the charging opportunity of
the battery 40, the number of times the engine 31 is driven based
on requests from the air-conditioning system 10 can be reduced.
[0114] In the descriptions above, the configuration of the cold
storage material 18a may be omitted. In this case as well, output
control of the engine 31 such that the engine operating point is in
the high-efficiency region F0 and the process for stopping output
control during the cold release period can be alternately
performed. As a result, suitable engine control can be actualized
without excessively introducing surplus power for
air-conditioning.
[0115] In the descriptions above, the cold storage material 18a and
the evaporator 18 may be configured such as to be separate units as
in the modified example of the air-conditioning system in FIG. 10.
For example, as shown in FIG. 10A, the evaporator 18 and the cold
storage material 18a may be provided in parallel. In addition, as
shown in FIG. 10B, the evaporator 18 and the cold storage material
18b may be provided in series.
[0116] In the descriptions above, an example of the
air-conditioning system 10 that uses an electric compressor is
given. However, the compressor 11 of the air-conditioning system 10
may be a mechanical type, as shown in the modified example of the
air-conditioning system in FIG. 11. In this case, the compressor 11
and the engine 31 are connected by a connecting member (no
reference number given), such as a belt. Driving force from the
engine 31 is transmitted to the compressor 11 via the belt. In FIG.
11, a transmission 41 is connected between the engine 31 and the
differential gear 36.
[0117] In the processes in FIG. 4 and FIG. 8, described above,
engine output may be controlled such that the engine operating
point becomes closer to the maximum efficiency point within the
high-efficiency region F0. In other words, the engine ECU 21 may
determine YES in the processes at step S23 in FIG. 4 and step S41
in FIG. 8, when the engine operating point becomes closer to the
maximum efficiency point.
[0118] The correspondence between the terms used in the
above-described embodiments and the terms used in the claims is as
follows. The engine ECU 21, which includes a microcomputer
(including a CPU, a ROM and a RAM), corresponds to an example of a
control apparatus that functions as an allowed/not-allowed
determiner means (or an allowed/not-allowed determiner) and a
controller means (or a controller). The cold storage material 18a
corresponds to an example of a cold storage means. The motors 32
and 33 corresponds to an example of a power generator means. The
control apparatus may further function as an increasable output
calculator means (or an increasable output calculator) and a
determiner means (or a determiner). In this case, the control
apparatus may also function as an output controller means (or an
output controller). The control apparatus may further function as a
compressor drive determiner means (or a compressor drive
determiner). In this case, the control apparatus may also function
as a decreasable output calculator means (or decreasable output
calculator) and a determiner means (or a determiner). The control
apparatus may further function as a request determiner means (or a
request determiner).
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